Respirator with nebulizer



Dec. 13, 1966 CARL-GUNNAR D. ENGSTRDM ETAL 3,

RESPIRATOR WITH NEBULIZER Filed Oct. 24, 1965 5 Sheets-Sheet 2 106-Z H07 104 110 k 7 1966 CARL-GUNNAR D. ENGSTRC'JM ETAL 3,291,122

RESPIRATOR WITH NEBULI ZER 3 Sheets-Sheet 3 Filed Oct. 24, 1963 United States Patent 3,291,122 RESPIRATOR WITH NEBULIZER Carl-Gunnar Daniel Engstrtim, Aluddsvagen 3, Stockholm, Sweden, and Paul Herzog, Nybodagatan 7, Solna, Sweden Filed Oct. 24, 1963, Ser. No. 318,716 Claims priority, application Sweden, Get. 25, 1962, 11,485/ 62 Claims. (Cl. 128-1458) The invention relates to respirators for artifical breathing and for narcosis of the type comprising a closed or semi-open conduit system for the respiratory gas, including a lung attachment adapted to connect said system with the lungs of a patient, and gas propelling means promoting the flow of the respiratory gas in the system and lungs, thereby periodically establishing in at least a high pressure portion of the system including the lungs, alternatively a relatively high gas pressure and a relatively low gas pressure. The invention is more particularly concerned with such respirators equipped with means for imparting an aerosol to the respiratory gas by means of a nebulizer or atomizer. In a positive or active inhalation phase of the respirator the breathing gas is forced into the lungs of the patient. The gas can be exhaled by the patient himself through the natural elasticity of the lungs, but the respirator may also have a positive or active exhalation phase when gas is sucked out of the lungs of the patient. The pressure in the high pressure portion usually varies from about atmospheric pressure, when active phase is used only at the inhalation, and from about cm. aq., when active phase is used at both inhalation and exhalation, to about 50 or 80 cm. aq. in both cases. The differential pressure is thus considerable.

It is previously known to atomize by the aid of an ejector a liquid in a gas to be inhaled by a patient, also in connection with artificial breathing. However, in this case the aerosol has been introduced into the inhalation gas just before the gas enters the lungs. it is also known to impart liquid drops in a finely divided state to a gas by passing the gas through a chamber having a liquid container and containing a supersonic vibrator so arranged that the supersonic waves are concentrated to the surface of the liquid whereby nebulization takes place. In known devices for nebulization in connection with artificial breathing it has proved difiicult adequately to dose and measure the liquid delivered in the form of a mist.

The invention has for its main object to make feasible a continuous dosage of aerosol to the respiratory gas which is subjected to the considerable pressure variations encountered in respirators operating with forced or positive pressure inhalation and possibly with forced or negative pressure exhalation. It is a further object to make possibie a more accurate dosage of the liquid required for a given demand and measuring of liquid consumed. It is a particular object, according to the preferred embodiments of the invention, to provide means for converting into aerosol essentially all liquid supplied for atomizing so that waste of or recirculation of liquid can be avoided.

These objects of the invention and other advantages will be obtained by incorporating in the high pressure portion of the closed or semiopen conduit system of the respirator a nebulizer comprising an atomizing (nebulizing) chamber including a gas space, a gas inlet and a gas outlet connecting said gas space with said gas propelling means and said lung attachment, respectively, a supersonic vibrator located in said chamber, and a conduit for supplying liquid to be atomized (nebulized) to said chamber, said conduit having an opening in said chamber exposed to pressure variations therein, and means for hampering reverse fiow in at least the portion of said liquid supply conduit near its opening in said chamber.

It is important that the more or less sudden and abrupt increase in pressure that arises when the inhalation phase is started does not provoke movements of the liquid to be atomized since such movements would be detrimental to the smooth atomization and the uniform supply of liquid to the point or place of atomization. The hampering of reverse flow of the liquid in the supply conduit, and more particularly in the portions thereof near its opening into the nebulization chamber, is therefore imperative. The hampering can take place in different ways. It may be effected by a throttle or a contracted portion, a constriction, in the supply conduit, which may in this case constitute a capillary tube, or it may be effected by a check valve or it may be effected by providing communication with the gas space of said atomizing (nebulizing) chamber at said opening of the conduit as well as at a position remote from said opening so that the liquid at said opening and at said position will always be exposed to the same gas pressure.

In the preferred embodiments of the invention the nebulizer comprises a substantially plane supersonic vibration plate located, preferably substantially horizontally, in the gas space of said nebulizer, the opening of said liquid supply conduit being positioned above and preferably centrally of said plate and being dimensioned and arranged to supply substantially not more liquid than what can be atomized by the supersoni vibrator. The liquid should with advantage be supplied drop-wise or possibly in a limited continuous stream so that the supply can be accurately controlled and regulated so that substantially all liquid supplied will become atomized and only insignificant quantities be left unatomized and possibly accumulated for re-use. As it is of a particular significance that the supplied liquid really lands on the vibration surface of the iquid inlet should open at a point close to said surface, without, however, coming into direct contact therewith. There should be a clearance of at least 0.1 mm. In this way it is very simple to measure the liquid supplied per unit of time and to check that the liquid is completely atomized. As at the same time the amount of inhalation gas per unit of time can be easily measured the dosage can be controlled with certainty. Various modifications of this embodiment will be described more in detail herein below with reference to the drawings.

According to the invention it is also possible to use the spherical vibrator type of nebulizer provided it be modified to respond to the demands set by the pulsating pressure in the conduit system. In this case the devices for hampering reverse flow in the liquid supply conduit is thus applied in a nebulizer comprising a spherical convergent supersonic vibrator plate so positioned at the bottom portion of the atomizing chamber of the nebulizer that its focus falls within said chamber above the plate, said liquid supply conduit opening into said chamber, and a liquid outlet in said chamber substantially at the level of said focus. In this embodiment liquid has to be supplied in a comparatively large quantity filling up the space above the vibrator up to a level near the focus and it must be supplied continuously in excess so as to warrant a fixed liquid level in the atomizing chamber, the excess overflowing the outlet. This is disadvantageous because it is diflicult to maintain a fixed liquid level and complicated to dispose of the overflow and possibly recirculate it. These drawbacks are not or only to an insignificant degree inherent in the embodiments referred to above, which are, moreover, less sensitive to slight variations in the inclination of the nebulizer.

The invention will now be described by the way of example with reference to a number of embodiments illustrated in the attached diagrammatic drawings, in which:

FIG. 1 illustrates a respiratory system comprising a nebulizer according to the invention with a plane supersonic vibrator and an external liquid container, FIGS. 2 and 3 show modified nebulizers with plane supersonic vibrators and internal liquid vessels, that of FIG. 2 being stationary and that of FIG. 3 being replaceable, and FIG. '4 illustrates a nebulizer with spherical supersonic vibrator, .FIG. 5 Showing a fragment of a supply conduit with a hampering constriction.

The upper portion of FIG. 1 illustrates a conventional respirator system and the lower portion shows on a larger scale a nebulizer incorporated in the conventional system as shown by the dash-dotted lines, the tube portion shown to the left of the figure in dotted lines indicating the pure conventional system.

The pressure source needed for the artificial breathing is here illustrated with a compressor 1 having a reciprocating plunger 2 causing in the compressor and the pipes connected thereto alternatingly pressure and suction on either side of the plunger 2. Thus, in its pressure stroke to the right plunger 2 pressure in pipe 5 and in the container 6 housing a resilient bladder 7 causing the bladder to collapse and force the gas contained therein to pass through conduit 10 into the main conduit 11 and through check valve 12 to conduit 14 containing the carbon dioxide filter 15. In the conventional respirator the compressed gas passes further over the pipe 17 to conduit 18 and, in one way or the other, into the lungs 20. [he conduit 21 leading from the lungs and containing a moist filter 22 opens in a low pressure container 24. The opening of conduit 21 is during the inhalation phase closed by a valve head 26 pressed against the opening by a spring 27 secured to the valve head and a resilient membrane of a cup 28 connected to the main conduit 11 by a pipe 29. When, during the inhalation phase, high pressure is produced in conduit 11 high pressure also resides in cup 28 pressing the valve head 26 against the opening of conduit 21, thus establishing the limit for the high pressure portion created in the system by the action of bladder 7 and comprising conduits 11, 14, 17, 18 and 21 as well as the lungs 20. When plunger 2 makes its reverse stroke, to the left, vacuum is created in pipe 5 and container 6 permitting bladder 7 to be inflated by gas taken through the pipe 10, in the first hand gas contained in conduit 11, thereby closing check valve 12. Through the low pressure conditions check valve 31 is opened so as to connect the sucking bladder 7 with pipe 32 leading to valve house 33 containing valve head 34 controlling the opening of pipe 36 connected to pipe 37 containing at its end a bladder 38 and being connected to a 3-way valve 40. Valve 40 in the position shown in the drawing connects pipe 37 with the low pressure container 24. During the suction stroke of plunger 2 the exhalation phase is created in the system and low pressure is built up in the low pressure container 24 through the conduits and parts described which results in the opening of valve head 26 so that gas contained in the high pressure portion, including the lungs, passes from conduit 21 to low pressure container 24 through 3-way valve 40, conduits 37 and 36, valve house 33, pipe 32 to conduit 11 and bladder 7, bladder 38 being a pressure equalizer.

Gas consumed in the system can be replaced, for instance, by air through valve 43, by oxygen through valve 44, and with e.g. laughing-gas (nitrous oxide) for narcosis through valve 45.

As now described the respirator operates with fully closed system. The low pressure container 24 can be connected directly with the surrounding atmosphere by switching over the 3-way valve 40 to connect container 24 through pipe 47 and the Venturi pipe 48 with the atmosphere. This is a semiopen system. The exhalation can take place under artifical suction by connecting the Venturi 50 with the compressor 1 by opening valve 51 in pipe 52 containing check valve 53. The gas being exhausted no circulation of the gas takes place in the system which is then operating with air through valve 43 or other gases taken through valves 44 and 45.

From the above description, it will be understood that the respirator described can operate in various ways, more or less closed, but it is common to all ways of operation that in the high pressure portion, the pressure varies considerably during the periods of inhalation and exhalation, as mentioned above.

An aerosol prepared by supersonic vibration is introduced into the system shown in FIG. 1 by incorporating in the high pressure portion of the conduit system in the place of pipe 17 the nebulizer generally indicated by numeral 61 in the lower portion of FIG. 1. The nebulizer consists of a container having side walls 62, a bottom 63 and a removable lid 64 secured to the side wall 62 under the intermediation of a gas tight packing 65, said parts forming an atomizing chamber, in this case forming a gas space 68. The nebulizer has a gas inlet 69 connected to the conduit 14 and a gas outlet 70 connected to conduit 18 leading to the lungs 20. At the bottom of the nebulizer there is fitted a supersonic vibrator 72 having a plane vibrator plate 73 and being supplied with high frequency current through the coaxial cable 74, the details of the vibrator being explained more in detail in connection with FIG. 2. At the bottom there is also a drain pipe 76 with a cock 77. The liquid to be atomized is supplied from a store bottle 80 suspended from a bracket 81. The bottle may be an ordinary hospital drop flask used for continuous supply of blood or blood substitute or other liquids to patients. Bottle 80 is suspended upside down and is sealed with a plug 82 through which there is passed a liquid supply pipe 83 and an air admitting pipe 84 reaching up to the bottom of the bottle. As liquid is consumed, it is replaced by air entering through pipe 84. Liquid passes from bottle 80 through rubber tube 86, when jam-nut 87 is opened, to the liquid supply conduit 88, which is passed through lid 64 by an air-tight plug 89 so as to open the some distance above the vibrator plate 73. It could be brought close to said plate but owing to the difiiculty in accurately setting the conduit to appropriate distance above plate 73 a funnel 91 is preferably placed between the opening of conduit 88 and the plate 73. The opening 92 of the funnel can be set with precision at the desired distance above plate 73, which is at least 0.1 mm. and is with advantage 12 mm. The supply conduit 88 is here supposed to be a capillary tube or having a capillary portion at its opening 90, the capillary diameter being, for instance, 0.1-0.2 mm.

By hanging the bottle 80 at appropriate height above the nebulizer, the desired flow of liquid can be attained, about 10 to 20 drops per minute usually being a suitable amount. Although the amount of liquid supplied should be estimated to be fully atomized, it happens that liquid splashes from the vibrating plate 73. In order to collect the splash and re-feed it to the plate 73, bafile means are preferably arranged above and along the peripheral portions of the vibration plate. As illustrated the baffle means consists of a pervious structure 95 of truncated conical shape having openings 96 shaded by shields 97. The structure may consist of a series of circular strips inwardly inclined and arranged somewhat apart one above the other with upwardly increasing diameters so as to form a structure similar to that illustrated in the drawing.

In order to facilitate the transfer of the liquid from the funnel, or from the opening of the liquid supply conduit in case no funnel is used, onto the plate 73 a leader thread 98 may be passed from the opening 92 or 90 of said liquid supply conduit 88 or of said funnel 91, respectively, to or to the neighborhood of the vibrator plate 73.

The supersonic vibrator 72 is illustrated more in detail in FIG. 2. Its vibrator plate 73 is in electrically leading connection through the housing 101 and thread 102 with the metallic shielding layer 103 of the coaxial cable 74. The central wire 104 of the cable is in contact with a metallic bottom plate 106 with a wound portion 107 in order to warrant a resilient contact. Bottom plate 106 and vibrator plate 73 are separated by a plate 109 of piezoelectrical material. The metallic portions 103 and 104 of the cable are separated by insulating material 110.

The embodiment illustrated in FIG. 2 is incorporated in the respirator by its inlet 69 and outlet as the embodiment shown in FIG. 1. This nebulizer differs from that described above in the means for liquid supply. From lid or a cover 64 projects downwardly an angular flange 112 having threads 113 on its outer face. Screwed onto flange 112 is a liquid vessel 115 with threads cooperating with threads 113. There is a liquid space 116 in the vessel and a liquid supply conduit 83 is passed through the bottom of vessel 115 so as to connect the bottom portion of the liquid space 116 with the vibrator plate 73 generally as described above. A series of openings 117 in the upper portion of vessel 115 eonnect the space above the liquid in the vessel with the gas space 63 of the atomizing chamber of the nebulizer. Conduit 88 is dimensioned so as to supply appropriate amount of liquid to plate 73 and since the opening of conduit 88 and the upper surface of the liquid in vessel communicate with gas space 68 the pressure variations in the gas space have no influence upon the liquid supply. The diameter of vessel 115 is with advantage large and the height of the liquid space 116 low in order that the height variation during the consumption of the liquid shall not be too great. This vessel constitutes an irremovable part of the nebulizer. The vessel can be replenished with liquid either by removing the plug 89 and filling in new liquid or by the arrangement shown in FIG. 2 comprising a pipe 120 passed through the plug 89 and containing a valve or cock 121. The pipe 120 may with advantage be connected to a liquid container 123. If it is desired to make feasible to replenish vessel 115 without interrupting the operation of the respirator, it is advantageous to press the liquid into vessel 115. In such case a plunger 124 may be arranged in container 123, and after opening valve 121 plunger 124 may be pressed downward with rod 125.

The embodiment illustrated in FIG. 3, similarly to that of FIG. 2, has a vessel inside the nebulizer 61. In this case the vessel is separate and removable so that it can be admitted to and removed from the nebulizer through an opening 131 in the upper wall 132 of the nebulizer, the opening being closeable with a cap 133 threaded onto a nipple 134. A gas tightening packing 135 is placed in the cap 133. The removable vessel 130 is fitted in a vessel holder 137 and has a bottom 1313 and a top closure 139, which can be punctured by a liquid supply conduit 88 and any convenient needle or cannula 141 or the like. Conduit 88 and/or needle 141 may be syringe needles which are easily available at a hospital and the bottom and top portions 138 and 139 may be of rubber. In order to warrant free communication between the gas space 63 with the opening 90 of conduit 88 as Well as the gas space 143 above the liquid in the vessel communication openings 144 are provided in the vessel holder 137. Instead of the needle 141 communication with the gas space 143 can be obtained by simply rupturing the top closing member 139. This nebulizer is attached to the respirator by its inlet 69 and outlet 70 as described above with reference to FIGS. 1 and 2.

As illustrated in FIG. 3 the conical bafile means 95 can be made from a plate bent to truncated conical shape in which openings 96 are made by pressing with an adequately shaped stamp so as to bend a portion 97 of the plate inwardly. I

In the embodiment shown in FIG. 4 the nebulizer 61 comprises a spherical convergent supersonic vibrator plate 151 fitted in an insulating ring 152 of, for instance, rubher, which is fitted in a shoulder 153 in the wall 154 of the nebulizer by the aid of a ring 155. Electric current is supplied through the coaxial cable 74 the metallic shielding socket 103 of which is electrically connected with the metallic wall 154 by the aid of a thread 102. The current wire 104 is passed through an insulating plate 158 into contact with the lower surface of vibrator plate 151 which has a metallic coating on both sides. In order to supply current to the upper coating a thread 159 is welded to the upper surface of plate 151 and to wall 154. When high frequency current is applied the spherical plate 151 gives rise to supersonic waves directed to the centre of the sphere, i.e. to a focus 161.

This nebulizer is attached to the respirator by means of the gas inlet 69 and gas outlet 70 as described in connection with the previous embodiments. In this case the nebulizer has to be filled with liquid 163 up to about the level of the focus 161. Liquid is supplied from a container 165 through a pipe 166 and the liquid supply conduit 88 which in this case has a hampering means in the form of a check valve 167. The check valve may be replaced by a constriction as illustrated in FIG. 5. The liquid level in container 165 should preferably be constant. Therefore, the liquid inlet 169 should be automatically controlled by a valve 170 governed by a floater 171.

In order that the level of the liquid 163 in the nebulizer 61 shall be constant an overflow 174 is arranged in the wall 154 of the nebulizer. The overflow 174 communicates with a release valve 175 arranged to let out the overflowing liquid through outlet 176. Since during the inhalation phase the nebulizer is to be put under high pressure the communication through outlet 176 must be closed and therefore a bladder 177 is placed in the valve house 178, the bladder being connected to the high pressure portion of the conduit system, as to the inlet 69 by the aid of a pipe 179.

In operation liquid is continuously or practically continuously flowing from container 165 through the liquid portion of the nebulizer 61 over the overflow 174 through the open valve 175 to the outlet 176 and the vibrations of vibrator plate 151 causes liquid to be atomized at the focus region 161. In the active inhalation phase gas is passing through inlet 69 and due to the high pressure transmitted through pipe 179 bladder 177 is inflated and presses the valve 175 into closed position. The gas is passed near the region where liquid is atomized and passes to the outlet 70, baflles 182 being arranged for preventing splashing liquid to be entrained with the gas leaving at the outlet 7 0. During this phase liquid is prevented from reverse flow in the supply conduit 88 by the check valve 167, or-constriction according to FIG. 5. The plate 151 may be parabolic.

The constriction shown in FIG. 5 is effective as it upsets an effective obstruction during the relatively short period of time under which the system is under high pressure. As a principle this constriction can be used in any embodiment referred to above.

The invention has been described with reference to one type of conventional respirator, but it is to be understood that any respirator system may be used provided its lung attachment is exposed to pressure variations due to the artificial pressing of breathing gas into the lungs. Thus, the pressure source may be a bellows or bag instead of a compressor. It is also possible to let the breathing gas pass directly through the compressor, bellows or bag, with the exclusion of bladder 7.

What is claimed is:

1. Respirator for artificial breathing and for narcosis of the type comprising a conduit system for the respiratory gas, including a lung attachment adapted to connect said system with the lungs of a patient; a gas propelling means promoting the flow of respiratory gas in the system and lungs, thereby periodically establishing in at least a high pressure portion of said system including said lung att-achment alternatively a relatively high gas pressure and a relatively low gas pressure; a nebulizer incorporated in said high pressure portion of said system, said nebulizer comprising a nebulizing chamber including a gas space, a gas inlet and a gas outlet connecting said gas space with said gas propelling means and said lung attachment, respectively, a supersonic vibrator located in said chamber, a liquid supply conduit for supplying liquid to be nebulized to said chamber, said conduit having an opening into said chamber exposed to pressure variations in said chamber, and means for hampering reverse flow in at least that portion of said liquid supply conduit which is adjacent its opening in said chamber.

2. Respirator as claimed in claim 1, characterized by a throttle or constriction in said liquid supply conduit for hampering reverse flow therein.

3. Respirator as claimed in claim 1, characterized by a check valve in said liquid supply conduit for hampering reverse flow therein.

4. Respirator as claimed in claim 1, in which said liquid supply conduit communicates with the gas space of said nebulizing chamber at said opening of the conduit and also at a position remote from said opening so that the liquid at said opening and at said position will always be exposed to the same gas pressure.

5. Respirator as claimed in claim 1, in which said vibrator plate is a concave convergent supersonic vibrator plate and is positioned at the bottom portion of the atomizing chamber of the nebulizer so that its focus falls within said chamber above the plate, said liquid supply conduit opening into said chamber, and a liquid outlet in said chamber substantially at the level of said focus.

6. Respirator as claimed in claim 1, further including a substantially plane supersonic vibration plate substantially horizontally disposed in the gas space of said nebulizer, the opening of said liquid supply conduit being positioned above and substantially centrally of said plate and being dimensioned and arranged to supply substantially no more liquid than what can be atomized by the supersonic vibrator.

7. Respirator as claimed in claim 6, comprising a distributory funnel located below said conduit opening, so as to receive liquid supplied therethrough, and above said vibration plate, so as to feed the liquid so received onto said plate.

8. Respirator as claimed in claim 6, characterized by a leader thread passing from the opening of said liquid supply conduit to the neighborhood of said vibrator plate.

9. Respirator as claimed in claim 6, comprising bafile means arranged above and along the peripheral portions of said vibration plate to collect liquid splashed from said plate and re-feed it thereto.

10. Respirator as claimed in claim 6, in which said liquid supply conduit is connected to a liquid container located outside said nebulizer at a level high enough to enable liquid to flow therefrom into the nebulizer by gravity against the obstacle of said hampering means and the pressure therein.

11. Respirator as claimed in claim 6, comprising a vessel in said nebulizer, a space for a body of liquid in said vessel, at least one opening in said vessel connecting space above such body of liquid in the vessel with the gas space of the atomizing chamber of the nebulizer, said liquid supply conduit being connected to the bottom portion of said liquid space of the vessel.

12. Respirator as claimed in claim 11, in which said vessel constitutes an irremovable part of the nebulizer.

13. Respirator as claimed in claim 12, comprising a wall in said nebulizer, in the vicinity of said vessel, and a closable opening in said wall for replenishing said vessel with liquid.

14. Respirator as claimed in claim 12, comprising a replenishing conduit, one end of which conduit opens in or above said vessel and the other end thereof is attached to a liquid container outside the nebulizer.

15. Respirator as claimed in claim 11, comprising at least one separate removable vessel, an opening in said nebulizer for the admission and removal of said vessel to and from the nebulizer, and means for closing said opening.

References Cited by the Examiner UNITED STATES PATENTS 2,658,169 11/1953 Barret 128l72 3,232,292 2/1966 Schaefer 128l72 FOREIGN PATENTS 1,056,065 4/ 1959 Germany.

RICHARD A. GAUDET, Primary Examiner.

C. F. ROSENBAUM, Assistant Examiner. 

1. RESPIRATOR FOR ARTICIAL BREATHING AND FOR NARCOSIS OF THE TYPE COMPRISING A CONDUIT SYSTEM FOR THE RESPIRATORY GAS, INCLUDING A LUNG ATTACHMENT ADAPTED TO CONNECT SAID SYSTEM WITH THE LUNGS OF A PATIENT; A GAS PROPELLING MEANS PROMOTING THE FLOW OF RESPIRATORY GAS IN THE SYSTEM AND LUNGS, THEREBY PERIODICALLY ESTABLISHING IN AT LEAST A HIGH PRESSURE PORTION OF SAID SYSTEM INCLUDING SAID LUNG ATTACHMENT ALTERNATIVELY A RELATIVELY HIGH GAS PRESSURE AND A RELATIVELY LOW GAS PRESSURE; A NEBULIZER INCORPORATED IN SAID HIGH PRESSURE PORTION OF SAID SYSTEM, SAID NEBULIZER COMPRISING A NEBULIZING CHAMBER INCLUDING A GAS SPACE, A GAS INLET AND A GAS OUTLET CONNECTING SAID GAS SPACE WITH SAID GAS PROPELLING MEANS AND SAID LUNG ATTACHMENT, RESPECTIVELY, A SUPERSONIC VIBRATOR LOCATED IN SAID CHAMBER, A LIQUID SUPPLY CONDUIT FOR SUPPLYING LIQUID TO BE NEBULIZED TO SAID CHAMBER, SAID CONDUIT HAVING AN OPENING INTO SAID CHAMBER EXPOSED TO PRESSURE VARIATIONS IN SAID CHAMBER, AND MEANS FOR HAMPERING REVERSE FLOW IN AT LEAST THAT PORTION OF SAID LIQUID SUPPLY CONDUIT WHICH IS ADJACENT ITS OPENING IN SAID CHAMBER. 